Problem: Simplify the following expression: $k = \dfrac{p}{4} - \dfrac{7p}{6}$
Explanation: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $4$ and $6$ $\lcm(4, 6) = 12$ $ k = \dfrac{3}{3} \cdot \dfrac{p}{4} - \dfrac{2}{2} \cdot \dfrac{7p}{6} $ $k = \dfrac{3p}{12} - \dfrac{14p}{12}$ $k = \dfrac{3p -14p}{12}$ $k = \dfrac{-11p}{12}$